Systems and methods of employing HEPA air units as secondary air filters

ABSTRACT

Disclosed is a method of filtering air in a closed work environment that includes placing a primary air filter assembly in the closed work environment, where the primary air filter assembly includes a first air input and a first air output. The first air output is poised to emit once-filtered air outside the closed work environment. The method also includes placing a secondary air filter assembly in the closed work environment, where the secondary air filter assembly includes a second air input and a second air output. The method continues with repositioning the first air output to feed the second air input of the secondary air filter assembly, where the second air output is positioned to provide twice-filtered air to the closed work environment, and operating the primary air filter assembly and the secondary air filter assembly simultaneously.

CROSS-REFERENCE TO RELATED APPLICATIONS

Not applicable.

STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT

Not applicable.

THE NAMES OF THE PARTIES TO A JOINT RESEARCH AGREEMENT

Not applicable.

REFERENCE TO AN APPENDIX SUBMITTED ON A COMPACT DISC AND INCORPORATED BYREFERENCE OF THE MATERIAL ON THE COMPACT DISC

Not applicable.

STATEMENT REGARDING PRIOR DISCLOSURES BY THE INVENTOR OR A JOINTINVENTOR

Reserved for a later date, if necessary.

BACKGROUND OF THE INVENTION Field of Invention

The disclosed subject matter is in the field of air filtration,specifically negative pressure high efficiency particulate air (HEPA)air filtering in a work environment for the control of asbestos andparticulate matter.

Background of the Invention

In a work environment as found at construction sites, hospital cleanrooms, manufacturing facilities, and the like, there is a need forremoving hazardous asbestos, dust, bacteria, and other particulates fromthe ambient air. Typically, a work area is sealed off from the outsideenvironment and an air filter assembly is placed within, with theexhaust air being ducted to outside the area.

U.S. Government regulations, issued by the Centers For Disease Control(CDC), require that work in sensitive areas, such as repair orconstruction work in hospitals, pharmacies, prisons, and the like bemonitored and controlled. Particulates, such as asbestos or othercontaminants, that can be potentially disturbed during construction orrenovation require control barriers to prevent the spread ofcontamination via air currents. These controls include maintaining anegative pressure environment throughout the work area for the durationof the work, and using an “exhaust to outside” rule where filtered airmust be ducted to outside the building during construction and repairs.

Ducting the filtered air outside the work area requires filtered air tobe ducted a significant distance away from the work area to exit thebuilding. Extensive ducting of filtered air is expensive,time-consuming, and often impractical. Ducting is also unrealistic forinterior rooms of a large facility, causing increased labor costs andinconvenience for personnel in nearby spaces. Ducting air to outside thebuilding can also dislodge debris in a ceiling during installation andcan contaminate additional areas. Therefore, there is a need to provideHEPA filtering of a closed room without the need to duct the filteredair out of the building.

SUMMARY OF THE INVENTION

In view of the foregoing, an object of this specification is to disclosea method of filtering air in a closed work environment that includesplacing a primary air filter assembly in the closed work environment,where the primary air filter assembly includes a first air input and afirst air output. The first air output is poised to emit once-filteredair outside the closed work environment. The method also includesplacing a secondary air filter assembly in the closed work environment,where the secondary air filter assembly includes a second air input anda second air output. The method continues with repositioning the firstair output to feed the second air input of the secondary air filterassembly, where the second air output is positioned to providetwice-HEPA filtered air to the closed work environment, and operatingthe primary air filter assembly and the secondary air filter assemblysimultaneously.

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS

Other objectives of the disclosure will become apparent to those skilledin the art once the invention has been shown and described. The mannerin which these objectives and other desirable characteristics can beobtained is explained in the following description and attached figuresin which:

FIG. 1 illustrates a system block diagram of an air filtration system ina closed environment using a primary filtration assembly and a secondaryfiltration assembly attached to the output of the primary filtrationassembly;

FIG. 2 illustrates an isometric view of a first air filter assembly;

FIGS. 3 and 4 illustrates side and top views of the air filter assemblydisclosed in FIG. 2;

FIGS. 5-8 illustrates isometric, side, and top views of a second airfilter assembly with a water column gauge;

FIGS. 9 and 10 illustrate isometric views of a third air filter assemblywith a circular cutaway region that uses standard and HEPA filterelements;

FIG. 11 illustrates an isometric view of a fourth air filter assemblywith an expanded outlet area;

FIGS. 12-14 illustrate isometric views of a fan motor assembly;

FIG. 15 illustrates a method flow diagram for filtering air in a closedarea using two filtering assemblies without ducting the exhaust airoutside of the closed area; and

FIGS. 16-18 illustrate front and side views of a floor mounted filterassembly.

It is to be noted, however, that the appended figures illustrate onlytypical embodiments of this invention and are therefore not to beconsidered limiting of its scope, for the invention may admit to otherequally effective embodiments that will be appreciated by thosereasonably skilled in the relevant arts. Also, figures are notnecessarily made to scale but are representative.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

Disclosed is a method of filtering air in a closed work environment thatincludes placing a primary air filter assembly in the closed workenvironment, where the primary air filter assembly includes a first airinput and a first air output. The first air output is poised to emitonce-filtered air outside the closed work environment. The method alsoincludes placing a secondary air filter assembly in the closed workenvironment, where the secondary air filter assembly includes a secondair input and a second air output. The method continues withrepositioning the first air output to feed the second air input of thesecondary air filter assembly, where the second air output is positionedto provide twice-filtered air to the closed work environment, andoperating the primary air filter assembly and the secondary air filterassembly simultaneously.

FIG. 1 illustrates a system block diagram of an air filtration system100 in a closed environment 102 using a primary filtration assembly 108and a secondary filtration assembly 120, where a secondary input 122 ofthe secondary filtration assembly 120 is attached to a primary output116 of the primary filtration assembly 108. In some embodiments, theclosed environment 102 is within a building or structure and contains aclosed environment atmosphere (atmosphere) 104 that is contaminated withparticulates such as construction dust, smoke, bacteria, asbestosparticles, and the like which as harmful to occupants of the building. Aregion of outside atmosphere 106 is also shown for comparison. The airfiltration system 100 includes a first duct 112 that accepts unfilteredair 114 from the atmosphere 104 and routes the unfiltered air 114 to aninput 110 of the primary air filtration assembly 108. The air filtrationsystem 100 also includes a second duct 118 that connects the primaryoutput 116 to a secondary input 122 of the secondary filtration assembly120, whereby partially- or first-filtered air from the primaryfiltration assembly 108 is routed to the secondary filtration system120. The air filtration system 100 also includes a third duct 126 thatroutes twice-filtered air 128 from a secondary output 124 to theatmosphere 104. Thus configured, the air filtration system 100 providestwice-filtered air 128 to the closed work environment 102 without theneed to route once-filtered air out of the closed work environment 102.

According to some embodiments, the secondary filtration assembly 120uses a HEPA air filter to allow the twice-filtered air 128 to exit thethird duct 126 within the closed work environment 102 and thus, withinan occupied building, facility, or public thoroughfare without the needfor extensive ducting to outside the building.

According to some embodiments, one or both primary and secondary airfilter assemblies 108, 120 operate as negative pressure filters.According to some embodiments, one or both one or both primary andsecondary air filter assemblies 108, 120 use HEPA or carbon filterelements.

According to some embodiments, it is advantageous to position one orboth the primary and secondary air filter assemblies 108, 120 outside ofthe closed work environment 102. This can be due to physicalconstraints, cost, time, and the like. In such embodiments, it can beadvantageous to redirect the flow of twice-filtered air back into thecloser work environment 102.

FIG. 2 illustrates an isometric view of a first air filter assembly 200.The first air filter assembly 200 includes a first body 202, a first airflow inlet 204, a first hinged door 206, a plurality of wheels (casters)208, and one or more first screened air outlets 210. In someembodiments, the first air flow inlet 204 is connected to flexibleductwork, such as second duct 118 of FIG. 1, and is 12 inches indiameter. However, other sizing and inlet options are possible and arenot limited by this disclosure. The first air filter assembly 200 ispowered by propane gas, natural gas, electricity, gasoline, and the liketo filter ambient air entering the assembly 200 via the first air flowinlet 204, filtering the air using filters, chemicals, and/orcentrifugal cleaners, traps and captures contaminants within theassembly 200 for later cleaning, and exhausts filtered air via the oneor more first screened air outlets 210. In some embodiments, theassembly 200 is mobile and is placed into position by using the attachedwheels 208, thus placing the assembly 200 in a desired position in acontaminated area of a building or construction site as described inFIG. 1.

In some embodiments, the first air filter assembly 200 performs thefunction of the secondary filtration assembly 120 of FIG. 1 by acceptingincoming air from the primary filtration assembly 108 and exhaustingtwice-filtered air 128 via the screened air outlets 210. In someembodiments, the screened air outlets 210 include baffles and/ordiffusers (not shown) to reduce air velocity or direct the flow offiltered air to desired directions or regions of the closed work space102. Other embodiments are possible and are not limited by theseexamples.

FIGS. 3 and 4 illustrates side and top views of the first air filterassembly 200 disclosed in FIG. 2.

FIGS. 5-8 illustrates an isometric, side, and top views of a second airfilter assembly 500 with a water column gauge. The second air filterassembly 500 includes a second body 502, a second hinged door 506, aplurality of wheels (casters) 208, and one or more second screened airoutlets 510. The second air filter assembly 500 is similar to the firstair filter assembly 200 disclose din FIG. 2 but includes the watercolumn gauge 512 used to measure and display pressure differentialbetween inlet and outlet pressures of the second air filter assembly500. The water pressure gauge 500 allows an operator to monitor therelative cleanliness and efficiency of a filter. When the pressuredifferential increases beyond a predetermined set point, the operatorknows that the filter is likely clogged and needs to be cleaned orreplaced. In some embodiments, the water pressure gauge often displaysthe pressure differential by using a water column in units of inches wc,inches Ag, or inches H2O, a non-SI standard measurement.

In some embodiments, the second air filter assembly 500 performs thefunction of the secondary filtration assembly 120 of FIG. 1 by acceptingincoming air from the primary filtration assembly 108 and exhaustingtwice-filtered air 128 via the second screened air outlets 510. In someembodiments, the second screened air outlets 510 include baffles and/ordiffusers (not shown) to reduce air velocity or to direct the flow offiltered air to desired directions or regions of the closed work space102. Other embodiments are possible and are not limited by theseexamples.

FIGS. 9 and 10 illustrate isometric views of a third air filter assembly900 with a circular cutaway region 904 that uses standard and HEPAfilter elements. The third air filter assembly 900 includes a thirdhinged door 906, a plurality of wheels (casters) 208, one or more thirdscreened air outlets 910, a mechanical or paper air filter element 912,and a HEPA filter element 914. The third air filter assembly 900 issimilar to the first air filter assembly 200 disclose din FIG. 2 butincludes the water column gauge 512 used to measure and display pressuredifferential between inlet and outlet pressures of the third air filterassembly 900. In some embodiments, the third air filter assembly 900includes one or more replacement doors (not shown) to allow access tothe interior of the third air filter assembly 900 for the purpose ofreplacing filters 912 and/or 914. Also in some embodiments, the thirdair filter assembly 900 includes an air gap (not shown) between the airfilter element 912 and the HEPA filter element 914. In some embodiments,the air gap is 8″ or 12″, but other dimensions are possible.

According to some embodiments, the third air filter assembly 900 isconstructed to accept a 2′ thick×24″ wide×24″ height filter element 912and a 12″×24″×24″ HEPA filter element 914. Other filter sizes arepossible and are not limited by this disclosure. For instance, thefilter could be 2′ thick×24″ wide×48.″ In some embodiments, the thirdscreened air outlets 910 include baffles and/or diffusers (not shown) toreduce air velocity or to direct the flow of filtered air to desireddirections or regions of the closed work space 102. Other embodimentsare possible and are not limited by these examples.

FIG. 11 illustrates an isometric view of a fourth air filter assembly1100 with an expanded outlet area. The fourth air filter assembly 1100includes a fourth body 1102, a fourth hinged door 1104, a plurality ofwheels (casters) 208, and one or more fourth screened air outlets 1110.The fourth air filter assembly 1100 is similar to the first air filterassembly 200 disclose din FIG. 2 but includes the water column gauge 512used to measure and display pressure differential between inlet andoutlet pressures of the fourth air filter assembly 1100 and an expandedair outlet area. The expanded air outlet area permits the fourth airfilter assembly 1110 to exhaust filtered air in multiple directions atonce, including all four horizontal directions and vertically. Accordingto some embodiments, the fourth air filter assembly 1110 uses HEPAfilter elements (not shown) as disclosed earlier. In some embodiments,the fourth screened air outlets 1110 include baffles and/or diffusers(not shown) to reduce air velocity or to direct the flow of filtered airto desired directions or regions of the closed work space 102. Otherembodiments are possible and are not limited by these examples.

FIGS. 12-14 illustrate an isometric and side views of a fan motorassembly 1200. The fan motor assembly 1200 includes a fan motor assemblybody 1202, a filter element 1204, an air inlet 1206, an inlet fan motor1208, and a three-speed fan switch box 1210. According to someembodiments, the inlet fan motor 1208 employs a squirrel-cage type fan.In some embodiments, the filter element 1204 is a paper filter while inother embodiments, the filter element 1204 is a HEPA filter. Inoperation, the fan motor assembly 1200 is energized by using thethree-speed fan switch box 1210 to control the speed of the fan motor1208. Ambient air is drawn into the air inlet 1206 and passes throughthe filter element 1204 before being exhausted out to the closed airenvironment 104 of FIG. 2.

FIG. 15 illustrates a flow diagram for filtering air in a closed areamethod 1500 using two filtering assemblies without ducting the exhaustair outside of the closed area. The method 1500 begins at block 1502where the primary air filter assembly is positioned in a closed workenvironment that requires filtering as described in FIG. 1. In someembodiments, the primary air filter assembly is the primary filtrationassembly 108 of FIG. 1. Next, at block 1504, an inlet air duct, such asfirst duct 112, is connected to the inlet of the primary air filterassembly. The inlet air duct directs contaminated ambient air of thework site and routes the air to the primary air filter assembly forfiltering.

Next, at block 1506, an additional secondary air filter assembly isplaced into the closed environment in proximity to the first air filterassembly. According to some embodiments, the secondary air filterassembly is the secondary air filtration assembly 120 of FIG. 1. Next,at block 1508, the air inlet of the secondary air filter assembly isconnected to the outlet of the primary air filter assembly via an airduct such as second duct 118. In this manner, first-filtered air outputfrom the primary assembly is injected into the inlet of the secondaryassembly for an additional round of filtering. Next, at block 1510, theoutlet of the secondary air filter assembly is routed within the closedenvironment. Finally, at block 1512, both the primary and secondary airfilter assemblies are operated simultaneously, thus providingtwice-filtered air back to the atmosphere of the closed workenvironment.

FIGS. 16-18 illustrate front and side views of a floor mounted filterassembly 1700. The floor mounted filter assembly 1700 includes a fanmotor assembly body 1202, a filter element 1204, an air inlet 1206, anda floor bracket stand 1702. In some embodiments, the filter element 1204is a paper filter while in other embodiments, the filter element 1204 isa HEPA filter. In operation, the filter assembly 1700 is positioned ontoa floor or other horizontal surface and remains stable due to thepresence of the floor bracket stand 1702. Ambient air is drawn into theair inlet 1206 and passes through the filter element 1204 before beingexhausted out to the closed air environment 104 of FIG. 2. According tosome embodiments, the floor mounted filter assembly 1700 is permanentlymounted to a horizontal surface, while in other embodiments, the filterassembly 1700 is mobile and is able to be moved into a preferredposition as needed. Other embodiments are possible and are not limitedby this disclosure.

According to some embodiments, this disclosure includes a method offiltering air in a closed work environment that includes placing aprimary air filter assembly in the closed work environment, where theprimary air filter assembly includes a first air input and a first airoutput, and where the first air output is poised to emit once-filteredair outside the closed work environment. The method also includesplacing a secondary air filter assembly in the closed work environment,where the secondary air filter assembly includes a second air input anda second air output, and repositioning the first air output to feed thesecond air input of the secondary air filter assembly, where the secondair output is positioned to provide twice-filtered air to the closedwork environment. The method also includes operating the primary airfilter assembly and the secondary air filter assembly simultaneously.

In some embodiments, the method also includes where at least one of theprimary air filter assembly and the secondary air filter assembly uses ahigh efficiency particulate air (HEPA) filter. In some embodiments, themethod also includes where at least one of the primary air filterassembly and the secondary air filter assembly operates as a negativeair pressure air mover. In some embodiments, the method also includeswhere at least one of the primary air filter assembly and the secondaryair filter assembly uses a carbon air filter. In some embodiments, themethod also includes where at least one of the primary air filterassembly and the secondary air filter assembly uses an air diffuser toreduce air velocity. In some embodiments, the method also includes whereat least one of the primary air filter assembly and the secondary airfilter assembly are positioned outside of the closed work environment.

According to some embodiments, this disclosure includes a system forfiltering air in a closed work environment that includes a primary airfilter assembly in the closed work environment, where the primary airfilter assembly includes a first air input and a first air output, and asecondary air filter assembly in the closed work environment, where thesecondary air filter assembly includes a second air input and a secondair output, and where the first air output feeds the second air input ofthe secondary air filter assembly to provide twice-filtered air to theclosed work environment.

In some embodiments, the system also includes where at least one of theprimary air filter assembly and the secondary air filter assemblyincludes a high efficiency particulate air (HEPA) filter. In someembodiments, the system also includes where at least one of the primaryair filter assembly and the secondary air filter assembly is a negativeair pressure air mover. In some embodiments, the system also includeswhere at least one of the primary air filter assembly and the secondaryair filter assembly includes a carbon air filter. In some embodiments,the system also includes where at least one of the primary air filterassembly and the secondary air filter assembly includes an air diffuserto reduce air velocity. In some embodiments, the system also includeswhere at least one of the primary air filter assembly and the secondaryair filter assembly are positioned outside of the closed workenvironment.

Although the method and assembly is described above in terms of variousexemplary embodiments and implementations, it should be understood thatthe various features, aspects and functionality described in one or moreof the individual embodiments are not limited in their applicability tothe particular embodiment with which they are described, but insteadmight be applied, alone or in various combinations, to one or more ofthe other embodiments of the disclosed method and assembly, whether ornot such embodiments are described and whether or not such features arepresented as being a part of a described embodiment. Thus the breadthand scope of the claimed invention should not be limited by any of theabove-described embodiments.

Terms and phrases used in this document, and variations thereof, unlessotherwise expressly stated, should be construed as open-ended as opposedto limiting. As examples of the foregoing: the term “including” shouldbe read as meaning “including, without limitation” or the like, the term“example” is used to provide exemplary instances of the item indiscussion, not an exhaustive or limiting list thereof, the terms “a” or“an” should be read as meaning “at least one,” “one or more,” or thelike, and adjectives such as “conventional,” “traditional,” “normal,”“standard,” “known” and terms of similar meaning should not be construedas limiting the item described to a given time period or to an itemavailable as of a given time, but instead should be read to encompassconventional, traditional, normal, or standard technologies that mightbe available or known now or at any time in the future. Likewise, wherethis document refers to technologies that would be apparent or known toone of ordinary skill in the art, such technologies encompass thoseapparent or known to the skilled artisan now or at any time in thefuture.

The presence of broadening words and phrases such as “one or more,” “atleast,” “but not limited to” or other like phrases in some instancesshall not be read to mean that the narrower case is intended or requiredin instances where such broadening phrases might be absent. The use ofthe term “assembly” does not imply that the components or functionalitydescribed or claimed as part of the module are all configured in acommon package. Indeed, any or all of the various components of amodule, whether control logic or other components, might be combined ina single package or separately maintained and might further bedistributed across multiple locations.

Additionally, the various embodiments set forth herein are described interms of exemplary block diagrams, flow charts and other illustrations.As will become apparent to one of ordinary skill in the art afterreading this document, the illustrated embodiments and their variousalternatives might be implemented without confinement to the illustratedexamples. For example, block diagrams and their accompanying descriptionshould not be construed as mandating a particular architecture orconfiguration.

All original claims submitted with this specification are incorporatedby reference in their entirety as if fully set forth herein.

What is claimed is:
 1. A method of filtering air in a closed workenvironment (102), comprising: placing a primary air filter assembly(108) in the closed work environment (102), wherein the primary airfilter assembly (108) includes a first air input (110) and a first airoutput (116), wherein the first air output (116) is a negative pressureair filter assembly that is poised to emit once-filtered air; placing asecondary air filter assembly (200) outside the closed work environment,wherein the secondary air filter assembly (900) includes a first body(202), a second air input (204), a first hinged door (206), a pluralityof wheels (208), and a screened second air output (210); opening thefirst hinged door (206); installing an air filter element (912) insidethe first body (202); installing a high efficiency particulate air(HEPA) filter (914) in the first body (202) and in between the airfilter element (912) and the hinged door (206); ensuring an air gapexists between the air filter element (912) and the HEPA filter (914);securing a flexible ductwork (118) to the first air output (116) and thesecond air input (204) so that the primary air filter assembly (108) isconfigured to feed the second air input (204) of the secondary airfilter assembly (200), wherein the second air output (210) is positionedto provide twice-filtered air (128) to outside of the closed workenvironment (102); operating the primary air filter assembly (108) andthe secondary air filter assembly (200) simultaneously; and, measuringvia a water column gauge (512) the pressure differential between thesecond air input (204) and the screened second air output (210).
 2. Themethod of claim 1, wherein at least one of the primary air filterassembly and the secondary air filter assembly operates as a negativeair pressure air mover.
 3. The method of claim 2, wherein at least oneof the primary air filter assembly and the secondary air filter assemblyuses a carbon air filter.
 4. The method of claim 3, wherein at least oneof the primary air filter assembly and the secondary air filter assemblyuses an air diffuser to reduce air velocity.
 5. A system for filteringair in a closed work environment, comprising: a primary air filterassembly in the closed work environment, wherein the primary air filterassembly includes a first air input and a first air output; a secondaryair filter assembly (1200) outside the closed work environment, whereinthe secondary air filter assembly (1200) includes a second air input(1206 that has a inlet fan motor assembly and a second air output (1204)including a filter element, wherein the inlet fan motor assembly isenergized by using the three-speed fan switch box to control the speedof the inlet fan motor so that ambient air is drawn into the air inletand passed through the filter element (1204) wherein the first airoutput feeds the second air input of the secondary air filter assembly(1200) to provide twice-filtered air to outside the closed workenvironment.
 6. The system of claim 5, wherein at least one of theprimary air filter assembly and the secondary air filter assemblyincludes a high efficiency particulate air (HEPA) filter.
 7. The systemof claim 6, wherein at least one of the primary air filter assembly andthe secondary air filter assembly is a negative air pressure air mover.8. The system of claim 7, wherein at least one of the primary air filterassembly and the secondary air filter assembly includes a carbon airfilter.
 9. The system of claim 8, wherein at least one of the primaryair filter assembly and the secondary air filter assembly includes anair diffuser to reduce air velocity.